The present invention relates to a process and a device for detecting revolution of a rotating element, and in particular to such a process and device in which the rate of rotation of a rotating part enclosed by a housing is measured.
To determine the rate of rotation of rotating parts, markings which are generally arranged at the rotating part are sensed by an inductive transmitter or an optical sensor. When such marks pass by the stationary transmitter, voltage pulses are generated, the rate of rotation being calculated from the repetition rate of these voltage pulses.
It is not possible to calculate the rate of rotation in this way in the case of rotating parts which are completely enclosed by a housing. For example, in electric fuel pumps which are completely encapsulated, no rotatable parts are guided outward which would make it possible to determine the rate of rotation in a simple manner. For this reason, signals dependent on the rate of rotation have been analyzed in laboratory tests for determining the rate of rotation, e.g.: the oscillation acceleration on the electric fuel pump housing, fluctuations in pressure on the suction side or the pressure side, fluctuations in current in the electric supply lines, fluctuations in the magnetic field outside the electric fuel pumps which are caused by the rotating armature segments with the respective current-carrying alternations.
These signals were determined, for example, by separate sensors and processed in a subsequent evaluating arrangement. Determining the rate of rotation by measuring the intervals between individual oscillations has not proven reliable in the above-mentioned laboratory tests.